1. Field:
The present invention relates to a generator circuitry for connecting a generator to or disconnecting the same from a bus connected to a power supply.
2. Prior Art:
FIG. 1 schematically shows a known ordinary generator circuitry employed for connection or disconnection of a generator (3) to or from a bus (2) connected to an AC power supply (1). The circuitry comprises a first connector (4), a breaker (5), a second connector (6) and a main transformer (7) which are connected in series with one another in this order between the bus (2) and the generator (3).
FIG. 2 is an equivalent circuit diagram of the generator circuitry of FIG. 1, wherein there are shown an internal inductance (1a) of the power supply (1), an internal inductance (3a) of the generator (3), a capacitance (8) of a capacitor inserted between the ground and the joint of the first disconnector (4) and the breaker (5), a capacitance (9) of a capacitor inserted between the ground and the joint of the second disconnector (6) and the generator (3), and a capacitance (5a) of an interelectrode capacitor in the breaker (5).
In such a generator circuitry, an operation of connecting the generator (3) to or disconnecting the same from the power supply (1) is performed by closing or opening the breaker (5) in the state where the power supply (1) and the generator (3) are synchronized with each other. During this operation, the two disconnectors (4) and (6) connected to the two sides of the breaker (5) are kept closed.
When it becomes necessary to open the first disconnector (4) or the second disconnector (6) posterior to disconnection of the generator (3), each of such disconnectors needs to interrupt the charge current flowing to the capacitance of the interelectrode capacitor in the breaker (5). Particularly under such condition that there exists a great voltage phase difference between the power supply (1) and the generator (3), the interelectrode voltage applied between the two disconnectors (4) and (6) reaches a high level since the terminal voltage across the capacitance (5a) is high. Such a high interelectrode voltage renders severe the condition for interruption of the charge current while causing generation of an abnormally high voltage due to reignition. Therefore, it is requisite for each of the disconnectors (4) and (6) to have a sufficient capacity to withstand such a high voltage, hence inducing a disadvantage that the generator circuitry becomes dimensionally large.